The invention relates to a locking element for a row of blades of a turbomachine and to a turbomachine.
A known construction principle for rows of blades, in particular for rows of rotating blades, of a turbomachine, such as an aircraft engine, a stationary gas turbine, or a steam turbine provides for inserting blades of the respective rows of blades with their roots in an anchoring groove on the rotor side. In the radial direction, the blades are held by their roots in form-fitting manner in the anchoring groove. In the peripheral direction, locking in position is produced by a locking element that is inserted in the anchoring groove. A known locking element has a basic body that has a front bearing surface and a back bearing surface for form-fitting with opposite-lying groove surfaces, a front lock projection and a back lock projection for engaging in opposite-lying recesses of the anchoring groove, and a threaded region for interacting with a tightening element. After introducing the blades into the anchoring groove, the locking element is inserted, moved into its peripheral position, and brought into its locking position by the tightening element or it is tightened from below against the groove surfaces. In this case, a plate-shaped bridge element is disposed between the locking element . . . so that it is pressed from above against the groove surfaces during the tightening of the tightening element, whereupon the locking element is tightened from below against the groove surfaces. Such a construction principle is shown in U.S. Pat. No. 7,708,529 B2 of the Applicant as the prior art. A locking element that interacts with a screw and a plate-shaped bridge element is also known from U.S. Pat. No. 4,859,149. A threaded borehole passes through the locking element, and a screw is screwed into the borehole. The bridge element is disposed between the locking element . . . *, and, in combination with the screw, effects a lifting or locking of the locking element against the groove surfaces of the anchoring groove. It has been shown, however, with these principles, that the locking element can be screwed by its inner side radially outward, due to the construction, whereby the lock projections do not engage in the recesses on the side of the groove and the blades are not locked relative to the periphery and can disintegrate.
In addition, a locking of rotating blades in the peripheral direction is realized in U.S. Pat. No. 7,708,529 B2 in that the anchoring groove has crenelated radial projections through which locking pins pass axially and thereby form lateral stops for the rotating blades.
A locking element that has a threaded borehole passing through it for receiving a screw in the vertical direction is shown in CA 2829460 A1 and in GB 2 156 908 A. By screwing in the screw, the latter is supported at the base of the groove and thereby raises the locking element against corresponding groove surfaces. For interacting with so-called closure blades, the locking element has a tube-like projection or a collar that concentrically surrounds the threaded borehole.
Locking elements that are threaded onto a wire ring inserted into an anchoring groove are known from U.S. Pat. No. 4,255,086.